Orthopedic deformities are the deformities involving the musculoskeletal system. Hands, legs, spine, elbows and shoulders are the commonly observed parts of the bony anatomy to be affected by deformities. A typical treatment measure for the afore-stated afflictions in younger patients or children consists of bringing the deformed bony anatomy to the expected position and implanting metal rods, also known as growing rods, thereon to maintain the desired position; thereby correcting the deformity while enabling growth of the child.
Scoliosis is a classic example of orthopedic deformity wherein the patient presents with a C- or S-shaped curve in the spine, when viewed from the posterior side. Early Onset Scoliosis (EOS) is a variant of scoliosis that is typically observed in children below 10 years of age. In EOS, the degree of curve of the deformed spine may remain constant or may change with the passage of time. Pain is typically not present, however, the condition may reduce the thoracic cavity space which severely compromises the lung growth and function resulting in fatalities including death. Further, the treatment regime includes surgically implanting growing rods along the deformed spine at the first incidence and following it up with periodic surgeries to manually distract the rod to match the growth of the patient. The periodic surgeries can be as frequent as every six months and are associated with risks such as skin infections, and pulmonary complications, besides overnight hospitalization for monitoring purposes. Even further, young children with severe spinal deformities often have multiple other medical complications resulting in an overall compromised health status and quality of life. The stress from repeated surgeries also becomes overly burdensome for the patients and their families. The currently used growing rod systems require external stimuli and apparatus for distraction. The stimulation is classified into manual stimulation, mechanical stimulation and magnetic stimulation.
Manual distraction is the procedure which requires the surgeon to reopen the original incision, reach the implanted rod and physically distract the same using his hands. This procedure is to be repeated every time depending on the extent of the growth of the patient. Rod breakage, skin infections, wound complications and the like are the various drawbacks associated with the manual distraction process.
Use of growing rods with sliding mechanism is an example of mechanical distraction. Dual metal rods are fixed posteriorly to the corrected apex of the spine with a limited number of contact points to allow vertebral growth. The technique allows growth through passive sliding of the rod through the attachment. However, the mechanical sliding action creates metal wear debris and results in tissue necrosis. Further, the implant tends to protrude from the back of the patient and causes skin infections due to the open-ended sliding rod.
Magnetic growing rods involve the use of an external magnet to distract the rod. The disadvantage of using this technology is that the rod has to be implanted closer to the skin to enable effective actuation. Being closer to the skin increases the chances of wound complications, prominent protrusions and more unplanned surgical procedures. Further, such a placement necessitates that the rod has lesser points of attachment to the spine, with a much longer length of the rod remaining unsupported. This may result in stress fractures in the rods and may also cause screw pullout. Although the magnetic system does not need invasive procedures, it needs stringent follow—up procedures. Many times, these distractions are based on the measurements done on previous patients and may lead to miscalculated distractions in some patients leading to instrumentation failure.
Growing rods working on the principle of hydraulics are also disclosed in the prior art. However, the afore-stated rods need external stimuli to cause the distraction which involves repetitive surgical interventions by surgeons that can prove to be expensive. This is notwithstanding wound complications, prominent protrusions and infection which is the risk associated with repeat surgical interventions.
In view of the severe disadvantages associated with the growing rods currently used for deformity correction, the dire need for developing growing rods which operate without any external driving force is apparent. The inventors of the present disclosure provide self-actuating growing rod systems for orthopedic deformity correction which addresses the afore-stated concerns.